Fiber optic power source for an electroencephalograph acquisition apparatus

Abstract

A reusable appliance for acquisition from a patient of EEG signals comprising a micro-miniature, micro-power, low noise multi-channel data-acquisition system powered by a fiber optic illuminator and photovoltaic cell thus eliminating the need for inductively coupled power converters. The appliance also uses disposable EEG electrodes which are similar in size and very low cost.

Description

[0001] This application claims the benefit of priority under co-pending United States Provisional Application No. 60 / 161,644, filed Oct. 27, 1999.FIELD OF THE INVENTION[0002] The current invention relates to the field of medical anesthesia. More particularly it relates to the field of electronic monitoring of a patient undergoing anesthesia, especially for use during and after surgical operations. The invention more specifically relates to the device used to acquire electrical electroencephalograph (EEG) signals used to monitor a patient's state of awareness, more specifically still to the device comprising and obtaining electroencephalograph signals from one or more electrodes attached to the patient's head.BACKGROUND OF THE INVENTION[0003] Traditionally in the administration of anesthesia it has been the practice for an anesthesiologist to use only clinical signs from the patient to estimate the depth of the patient's anesthesia before and during surgical procedures requiring anes...

AI Technical Summary

Benefits of technology

[0010] The reusable appliance of this invention comprises a micro-miniature, micropower, low noise multi-channel data-acquisition system powered by a fiber optic illuminator and photovoltaic cell, thus eliminating the need for inductively coupled power converters. The appliance uses disposable EEG electrodes which are similar in size and have an estimated cost to produce of approximately $0.02 each.

Problems solved by technology

That application describes, among other things, the signals which will be gathered from the patient's head and as well the information which will be produced for the anesthesia practitioner but does not disclose the most effective way of acquiring the raw signals from the patient's head.

Signal acquisition for patient monitoring use in the OR and ICU presents a number of design challenges that can and will effect the overall acceptance of the product based on its cost, ease of use and performance.

Although designed for "ease of use," a 7 lead device is inherently more difficult to use and expensive than, for example, a 3-lead frontal array.

Nevertheless, such disposable attachments cost on the order of two dollars to manufacture

In addition, the harsh EMI environment of the operating room challenges a monitoring system, since electrosurgical devices produce signals up to 1 billion times greater in amplitude than that of the EEG.

There are situations, however, where electrocautery is in close proximity to the PSA preamplifier and signal corruption occurs.

When this does happen, it either increases latency of a displayed index during artifact recognition and rejection, or increases signal variability and index magnitude when not recognized as artifact.

Another source of noise / artifact is caused by leadwire movement.

This type of artifact will also increase latency of the displayed index during artifact recognition and rejection and an increase in signal variability with a decrease in the computed index when not recognized.

Transformer isolated power supplies are useless in the presence of the high fields near an MRI as their cores become saturated rendering them totally in-effective.

In addition the, the leakage fields associated with these compromised inductors and transformers interferes with the sensitive measurements performed during MRI data acquisition.

Images